Hydraulic motor with piston holding means



Nov. 8, 1966 A. l. LOUHlO HYDRAULIC MOTOR WITH PISTON HOLDING MEANS 2 Sheets-Sheet 1 Filed March 1, 1965 Nov. 8, 1966 A. 1. LOUHIO HYDRAULIC MOTOR WITH PISTON HOLDING MEANS 2 Sheets-Sheet 2 Filed March 1, 1965 FIG. 5

United States Patent 3,283,668 HYDRAULIC MOTOR WITH PISTON HOLDING MEANS Aaro Ilmari Louhio, Helsinki, Finland, assignor to 0y Suomen Autoteollisuus AB, Helsinki, Finland Filed Mar. 1, 1965, Ser. No. 436,016 10 Claims. (CI. 9144) This invention relates to a hydraulic motor, especially for vehicles, comprising a stationary frame with several radially arranged cylinders, into which are arranged to and fro working pistons and a cam-ring rotating relative the frame in cooperation with the pistons, in which the cylinders are connected to a hydraulic pressure source by means of a valve unit.

A hydraulic wheel-motor of the above type works at a low revolution rate, and the same is intended for ternporary use, either after starting the motor of the vehicle or when driving in rough terrain. It is of the greatest importance here to be able to disengage the motor pistons while driving in normal road conditions. If the pistons cannot be disengaged from action, the motor can be damaged if the speed of the vehicle is continually kept too high. Loose pistons in the motor would already at lower speeds cause loss of effect and simultaneously produce disturbing, rattling sound.

In this respect the present invention has for its purpose to produce an improved hydraulic motor, which according to the invention is characterized therein that the same is provided with means whereby an external effect of pressure liquid is made to act on each of the pistons direct or by aid of the action of the pressure liquid upon the cut-off unit, so that each piston stops at the position it has in the respective cylinder at the moment the pressure effect ceases in the cylinders.

According to the invention there is produced a hydraulic motor in which the pistons when necessary in a simple way can be hydraulically disengaged from action by means of locking them in the cylinders.

The invention is more closely described by the following specification with reference to the accompanying drawings, in which FIGURE 1 is an axially vertical cross-section of an embodiment of a hydraulic motor according to the invention,

FIGURE 2 is a section of the motor on line IIII of FIG. 1,

FIGURE 3 is another embodiment of a hydraulic motor in an axially vertical cross-section,

FIGURE 4 is a section on line IV-IV of FIGURE 3, and

FIGURE 5 is a detail of the motor in enlarged scale.

The hydraulic motor shown in the drawings comprises in both of its embodiments a stationary cylindrical frame part 1, provided with several radially arranged cylinders 2. Into the cylinders are arranged to and fro working pistons 3, which are provided with rollers 4 pivoted to the pistons. To the main parts of the motor can also be included a cam-ring 6, which is pivotally mounted to the frame part by the bearing 5. The cam-ring 6 is provided with a waved inner surface 7, which acts in cooperation with the piston rollers. In this embodiment the hydraulic motor is provided with five cylinders and pistons, whereas the inner surface of the cam-ring in this case is provided with eight elevations and eight excavations.

Into the frame is pivoted a regulating valve 8, which is connected to the cam-ring so that it rotates with this. Each of the cylinders are by intake and exhaust channels 9 and 10 and through the regulating valve 8 connected to a pump (not shown), whichdepending on the position of the regulating valvein proper turns is pressing in the pressure oil into the respective cylinder.

3,283,668 Patented Nov. 8, 1966 The regulating valve 8 is having two separate oil channels 11 and 12. Both of these channels are in connection with their own, separate slit-groups 13 resp. 14, their opening situated at the cylindrical mantle of the regulating valve. In each of the slit-groups the number of slits is equal to the number of cams on the cam-ring, and the slits are arranged at equal distance from another. The slit-group 14 is displaced relative the slit-group 13 thus that the cent-re :lines for the slits of group 14 are situated in the centre of the adjacent slits of the group 13. The slit-groups 13 and 14 are arranged at such point in the regulating valve that they, when the motor is working, are rotating right against the intake channels 9 respective the outlet channels 10. A condition, which guarantees satisfactory working for the motor, is that the number of cams in the cam-ring is not equal to the number of cylinders in the motor. As the number of inlet and outlet channels in the frame is equal to the number of cylinders and as the number of slits in the regulating valve is equal to the number of cams in the cam-ring, there are always only the decided inlet and outlet openings through slits 13 and 14 coming int-o contact with the channels in such an order, that from the slits of the pressure channel there is an inlet open only to the cylinders in which the pistons are having an outward movement, and the slits of the return channel are open only to those cylinders in which the pistons are moving inwards.

The slits are dimensioned so that 'both the slits as well as the intermediate cams are of equal width, or such, that the cylinder openings are in an exactly correct relation with the slits in the regulating valve and the intermediate cams, whereby an exact timing is being attained.

When channel 11 is subjected to pressure, the pressure liquid flows, in accordance with the here above described, into those cylinders Where the outwards moving pistons are working, which due to the caused effect start to turn the cam-ring. The cam-ring, which thus is brought into rotation, forces with its cams the other pistons to move inwards in the cylinders, whereat the pistons are pressing the returning oil into channel 12. When the regulating valve connected to the cam-ring is rotating, further inlet openings are being contacted with the pressure channel at the moment the piston roller has passed a cam elevation. The cylinder inlet 9 which is subjected to pressure is being closed at the moment the piston has attained its utmost position, Whereafter the exhaust channel 10 immediately starts to open itself into the return channel 14 of the regulating valve. This rotary motion is thus continual, as there are always several pistons simultaneously in function, e.g., two or three pistons in a motor with five cylinders. Thus, when the pressure fluid is led into channel 11, the motor rotates in a certain direction, in which case channel 12 acts as returning channel. When channel 12 is connected to the pressure channel, the direction of rotation of the motor is reversed, in which case the channel 11 acts as returning channel.

The construction and function of the hydraulic motor, as far as it has been here above described, is mainly known per se.

According to the invention the embodiment illustrated in FIGURES l and 2 consists of a frame part 1 wherein the channel 15 is formed between two cylinders which extends through the frame, opening into the inner chamber 17 of a liquid-tight housing 16, formed by the structure construction of the cam-ring 6. At the opposite end of this channel is mounted a pipe connection 18 for a pressure pipe 19, connected to a pressure source device (not shown). As a device for the pressure source can suitably be used the hydraulic pump of the motor, and as pressure pipe there may be most suitably used the leakage duct of the motor, by which means the oil that leaks from the cylinders and passes the regulating valve can be returned to the hydraulic system.

When the use of the hydraulic motor is discontinued, the supply of the pressure oil to the regulating valve 8 has to be stopped and from the hydraulic pump the pressure liquid is to be led at an excess of pressure of about 1 at. through a pressure reducing valve and cut-01f valve into the chamber 17 via the channel 15. As the pistons are 'not subjected to any pressure at all when passing the regulating valve after the pressure supply to the valve has been stopped, the hydraulic pressure of the pressure liquid presses the pistons into their extreme inward positions, locking them into this position. When the motor is started anew, the pressure liquid at a pressure of 1 at. is flowing from the chamber 17 through channel and a return valve into the pressure liquid container of the systern, or alternatively may this cut-off valve be substitued by a three-way cock, which at one of its positions leads the returning oil-flow in its non-pressure state into a container.

In the embodiment shown in FIGURES 3-5 there is being formed in the frame between each of the cylinder pairs two channels 20 and 21, the former one leading to the pressure liquid channel 11 of the regulating valve and the latter one to the channel 12. At the end of both of these channels is arranged a return valve 22 resp. 23. There is further arranged in the frame a transversally running channel 24 at the end of each channel pairs 20, 21, with which the channels 20 and 21 are in connection through the valve balls 25 and 26 of the return valve. The springs 27 are pressing the balls against the valve seats in the channels, closing off the channels 20 and 21 from channel 24. The valve seats in the channels are further having a fine capillary chink, through which the channels are in contact with another, but the flow of liquid passing through the chink is'quite inconsiderable. One end of the channel 24 is closed and its other end opens into a cylindrical bore 28 made in the frame, into which bore there is arranged an axially movable piston 29. The stem 30 of the piston is guided by means of a steering part 31, screwed into the bore. Between the piston and the steering part is a spring 32 which presses the piston against the mouth of channel 24. Around that end of stem 30 which is turned towards the piston is arranged an O-ring packing 33.

In the illustrated embodiment there is arranged between all of the cylinders a similar bore with an axially movable piston. Onto all of the pistons there is pivoted by means of pins 34 a lock-ring 35, which is mutual for all of the pistons and arranged coaxially with the frame on one side of the pistons. In the lock-ring there is in the middle for each of the pistons a lock-wedge 36, and the piston is provided with a corresponding wedge-way 37 situated thus that when the piston in the cylinder has its inward limit position, the lock-wedge and the wedgeway are positioned exactly opposite another. The movable pistons and the lock-ring are in this case arranged mutually thus that when the pistons are in their inward limit position, the lock-wedges of the lock-ring slide into their corresponding grooves in the pistons, and, when the pistons are pushed in and the axially movable pistons are in their outward limit position, the lock-wedges are set free from the grooves in the pistons.

When the motor is started in any of the directions of rotation, the pressure liquid simultaneously flows into channels20 or 21 and presses up the valve ball in the corresponding return valve so that the oil can flow into the channel 24. When the pressure exceeds the effect of spring 32, the movable piston 29 shifts itself gradually towards the steering part 31, until the tightening packingring 33 is pressed against the steering part.

The ball-valve of the channel 20 or 21, which is subjected to pressure, is in the meantime a bit open, as there through the seat of the other ball-valve is continually percolating liquid ink channel 11 or 12, which are acting as an exhaust channel for the regulating valve 8. When the movable piston 29 has been brought into contact with the steering part, the lock-ring draws out the lock-wedges from the grooves in the pistons, whereupon the pistons are working freely.

After completed performance with the motor and the pressure in channel 20 or 21 ceases, also the pressure in channel 24 is stopped via the earlier stated capillary chinks. In here the spring 32 presses the movable piston against the mouth of channel 24. The wedges of the lock-ring are pressing against the sides of the pistons and when a piston by the cam-ring has been pressed into its deadpoint, the corresponding wedge slides into the groove in the piston. The sides of the locking grooves are somewhat conical, same as the sides of the wedges. In case the movable pistons for some reason should not be opening, although the pressure being connected to the motor, the piston can push loose the lock-ring, after the pressure in the cylinders having exceeded a certain limit.

As it appears from the above stated, it is not necessary for the function of the lock-ring, that there is being arranged as many of the bore-rings 28 and movable piston; 29 as what the number of cylinders is in the motor. as also the case is with the above defined advantageous em.- bodiment, because only two diametrically opposite mo!- able pistons can principally be considered as sufllciert. It is also possible, instead of using one mutual lock-rir g, for each of the pistons to use a separate lock-ring pivoted to the frame as a lever arm, in which case its end near 1st to the piston is provided with a lock-wedge, the onpnri e end of which being operated by a movable piston.

The drawings and the thereto adherent specification are naturally only intended for illustrating the inventive i a of the invention and thus not limiting the same to the herein described constructions.

What 1 claim is:

1. A hydraulic motor for the use in vehicles and the like comprising a stationary frame having a plurality of radially arranged cylinders, a piston reciprocally positioned in and cooperating with each of said cylinders, a cam-ring notatably mounted to said frame and positioned around said plurality of cylinders, each said piston having contact means at its outer end for engaging the inner surface of said earn-ring, a regulating valve having pressure channels connected between said cylinders and a first source of hydraulic pressure for selectively forcing each said piston outwardly and enabling each said piston to move inwardly in a time sequence corresponding to the relative radial and angular positions between said contact means and said cam-ring, respectively, a liquid-tight housing mounted to said frame and defining a chamber about said cylinders, and means for selectively increasing fluid pressure in said chamber relative to the pressure in said cylinders so that said chamber pressure is great enough to force said pistons inwardly.

2. A hydraulic motor as set forth in claim 1 wherein said means for selectively increasing relative fluid pressure comprises a channel having one end communicating with said chamber and a second source of high fluid pressure communicating with the other end of said channel.

3. A hydraulic motor as set forth in claim 2 wherein said second source supplies increase fluid pressure to said chamber when the pressure in said first source is reduced in order to stop the motor action, whereby the fluid in said cylinders is forced back toward said first source when said pistons are forced inwardly.

4. A hydraulic motor for the use in vehicles and the like comprising a stationary frame having a plurality of radially arranged cylinders, a piston reciprocally positioned in and cooperating with each of said cylinders, a cam-ring rotatably mounted to said frame and positioned around said plurality of cylinders, each said piston having contact means at its outer end for engaging the inner surface of said cam-ring, a regulating valve having pressure channels connected between said cylinders and a source of hydraulic pressure for selectively forcing each said piston outwardly and enabling each said piston to move inwardly in a time sequence corresponding to the relative radial and angular positions between said contact means and said cam-ring, and lock means engaging said pistons when the pressure from said source is removed from said regulating valve and each said piston is forced inward by said camring.

5. A hydraulic motor as set forth in claim 4 wherein said lock means comprises a lock-wedge mounted on said frame adjacent each piston and selectively movable in and out of locking engagement with its associated piston when the latter is in its inward position.

6. A hydraulic motor as set forth in claim 5 wherein lock-control channels are provided in said frame which communicate with said pressure channels of said regulating valve, bias means for urging each lock-wedge toward its associated piston, and wedge-lock control means connected to said channels for moving each lock-wedge out of locking engagement and in opposition to the bias when there is high pressure in said channels.

7. A hydraulic motor as set forth in claim 6 wherein a locking ring is provided on which each lock-wedge is mounted for providing simultaneous movement of all lock-wedges.

8. A hydraulic motor as set forth in claim 7 wherein said locking ring is coaxial with the radially extending cylinder arrangement.

9. A hydraulic motor as set forth in claim 7 wherein movable valves are provided bias to normally close the paths between said lock control channels and said wedge lock control means wherein said movable valves open when the pressure in said lock-control channels exceeds a predetermined magnitude, said lock-wedge control means comprising at least one cylindrical bore defined by said frame, a lock control piston movably guided in each said bore and biased toward its locking position and having one end mechanically connected to said locking ring and having its opposite end facing said lock-control channels whereby an increase in fluid pressure in said latter channels forces in opposition to the bais said lock control piston from the locked to the unlocked position.

10. A hydraulic motor for the use in vehicles and the like comprising a stationary frame having a plurality of radially arranged cylinders, a piston reciprocally positioned in and cooperating with each of said cylinders, a cam-ring rotatably mounted to said frame and positioned around said plurality of cylinders, each said piston having contact means at its 'outer end for engaging the inner surface of said cam-ring, a regulating valve having pressure channels connected between said cylinders and a source of hydraulic pressure for selectively forcing each said piston outwardly and enabling each said piston to move inwardly in a time sequence corresponding to the relative radial and angular positions between said contact means and said cam-ring, and means for maintaining each of said pistons in an inward position when the pressure in the regulating valve is changed to stop motor action.

References Cited by the Examiner UNITED STATES PATENTS 2,139,185 12/1938 Engel 91-44 2,444,391 6/1948 Whitfield 91-44 2,650,543 9/1953 Pauget 103-174 2,811,143 10/1,957 Baines et al. 91-180 3,002,462 10/1961 Raymond 103-174 3,179,016 4/1965 Thornton-Trump 91-205 MARTIN P. SCHWADRON, Primary Examiner.

P. E. MASLOUSKY, Assistant Examiner. 

1. A HYDRAULIC MOTOR FOR THE USE IN VEHICLES AND THE LIKE COMPRISING A STATIONARY FRAME HAVING A PLURALITY OF RADIALLY ARRANGED CYLINDERS, A PISTON RECIPROCALLY POSITIONED IN AND COOPERATING WITH EACH OF SAID CYLINDERS, A CAM-RING ROTATABLY MOUNTED TO SAID FRAME AND POSITIONED AROUND SAID PLURALITY OF CYLINDERS, EACH SAID PISTON HAVING CONTACT MEANS AT ITS OUTER END FOR ENGAGING THE INNER SURFACE OF SAID CAM-RING, A REGULATING VALVE HAVING PRESSURE CHANNELS CONNECTED BETWEEN SAID CYLINDERS AND A FIRST SOURCE OF HYDRAULIC PRESSURE FOR SELECTIVELY FORCING EACH SAID PISTON OUTWARDLY AND ENABLING EACH SAID PISTON TO MOVE INWARDLY IN A TIME SEQUENCE CORRESPONDING TO THE RELAITVE RADIAL AND ANGULAR POSITIONS BETWEEN SAID CONTACT MEANS AND SAID CAM-RING, RESPECTIVELY, A LIQUID-TIGHT HOUSING MOUNTED TO SAID FRAME AND DEFINING A CHAMBER ABOUT SAID CYLINDERS, AND MEANS FOR SELECTIVELY INCREASING FLUID PRESSURE IN SAID CHAMBER RELATIVE TO THE PRESSURE IN SAID CYLINDERS SO THAT SAID CHAMBER PRESSURE IS GREAT ENOUGH TO FORCE SAID PISTONS INWARDLY. 